RESUMO
Covering: 1995 to 2022Tumors possess both genetic and phenotypic heterogeneity leading to the survival of subpopulations post-treatment. The term cancer stem cells (CSCs) describes a subpopulation that is resistant to many types of chemotherapy and which also possess enhanced migratory and anchorage-independent growth capabilities. These cells are enriched in residual tumor material post-treatment and can serve as the seed for future tumor re-growth, at both primary and metastatic sites. Elimination of CSCs is a key goal in enhancing cancer treatment and may be aided by application of natural products in conjunction with conventional treatments. In this review, we highlight molecular features of CSCs and discuss synthesis, structure-activity relationships, derivatization, and effects of six natural products with anti-CSC activity.
Assuntos
Neoplasias , Humanos , Neoplasias/tratamento farmacológico , Neoplasias/patologia , Células-Tronco NeoplásicasRESUMO
The epithelial-mesenchymal transition (EMT) imparts properties of cancer stem-like cells, including resistance to frequently used chemotherapies, necessitating the identification of molecules that induce cell death specifically in stem-like cells with EMT properties. Herein, we demonstrate that breast cancer cells enriched for EMT features are more sensitive to cytotoxicity induced by ophiobolin A (OpA), a sesterterpenoid natural product. Using a model of experimentally induced EMT in human mammary epithelial (HMLE) cells, we show that EMT is both necessary and sufficient for OpA sensitivity. Moreover prolonged, sub-cytotoxic exposure to OpA is sufficient to suppress EMT-imparted CSC features including sphere formation and resistance to doxorubicin. In vivo growth of CSC-rich mammary cell tumors, is suppressed by OpA treatment. These data identify a driver of EMT-driven cytotoxicity with significant potential for use either in combination with standard chemotherapy or for tumors enriched for EMT features.
Assuntos
Neoplasias da Mama/patologia , Transição Epitelial-Mesenquimal , Fungos/química , Sesterterpenos/farmacologia , Animais , Neoplasias da Mama/genética , Morte Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Doxorrubicina/farmacologia , Células Epiteliais/efeitos dos fármacos , Células Epiteliais/patologia , Transição Epitelial-Mesenquimal/efeitos dos fármacos , Transição Epitelial-Mesenquimal/genética , Feminino , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Humanos , Camundongos SCID , MicroRNAs/genética , MicroRNAs/metabolismo , Proteínas Nucleares/metabolismo , Fenótipo , Proteína 1 Relacionada a Twist/metabolismoRESUMO
Pharmacophore-directed retrosynthesis applied to ophiobolin A led to bicyclic derivatives that were synthesized and display anticancer activity. Key features of the ultimate defensive synthetic strategy include a Michael addition/facially selective protonation sequence to set the critical C6 stereocenter and a ring-closing metathesis to form the cyclooctene. Cytotoxicity assays toward a breast cancer cell line (MDA-MB-231) confirm the anticipated importance of structural complexity for selectivity (vs MCF10A cells) while C3 variations modulate stability.
Assuntos
Antineoplásicos/síntese química , Antineoplásicos/farmacologia , Sesterterpenos/síntese química , Sesterterpenos/farmacologia , Antineoplásicos/química , Linhagem Celular Tumoral , Técnicas de Química Sintética , Humanos , Sesterterpenos/química , Relação Estrutura-AtividadeRESUMO
The deposition of the activating H3K4me3 and repressive H3K27me3 histone modifications within the same promoter, forming a so-called bivalent domain, maintains gene expression in a repressed but transcription-ready state. We recently reported a significantly increased incidence of bivalency following an epithelial-mesenchymal transition (EMT), a process associated with the initiation of the metastatic cascade. The reverse process, known as the mesenchymal-epithelial transition (MET), is necessary for efficient colonization. Here, we identify numerous genes associated with differentiation, proliferation and intercellular adhesion that are repressed through the acquisition of bivalency during EMT, and re-expressed following MET. The majority of EMT-associated bivalent domains arise through H3K27me3 deposition at H3K4me3-marked promoters. Accordingly, we show that the expression of the H3K27me3-demethylase KDM6A is reduced in cells that have undergone EMT, stem-like subpopulations of mammary cell lines and stem cell-enriched triple-negative breast cancers. Importantly, KDM6A levels are restored following MET, concomitant with CDH1/E-cadherin reactivation through H3K27me3 removal. Moreover, inhibition of KDM6A, using the H3K27me3-demethylase inhibitor GSK-J4, prevents the re-expression of bivalent genes during MET. Our findings implicate KDM6A in the resolution of bivalency accompanying MET, and suggest KDM6A inhibition as a viable strategy to suppress metastasis formation in breast cancer.